In order to isolate a building from vibration, a vibration isolation system for building should satisfy the following requirements:
1. allowing flexible sliding movements between the building and a bases;
2. having enough large initial rigidity;
3. having enough ability of damping and energy dissipation so as to limit the displacement of the building;
4. having functions of resetting the building.
The existing vibration isolation system for building is formed such that vibration isolation devices (rolling bearing vibration isolation devices or sliding bearing vibration isolation devices), elastic member horizon-resetting devices (rubber block or sandwiched rubber block horizon-resetting devices), damping and energy dissipation devices and so on are provided between movable bases and fixed bases which are positioned at the bottom of columns of the building. The rolling (or rollers sandwiched between sliding plates) bearing vibration isolation devices bear the vertical load of the building; the elastic member horizon-resetting devices and the damping and energy dissipation devices are generally positioned around the rolling bearing vibration isolation devices, wherein the elastic member horizon-resetting devices are used to reset the position of the building and the damping and energy dissipation devices are used to provide enough initial rigidity and energy dissipation ability so as to limit the relative displacement of the building to the base.
The Japanese Patent Publication No. 61135 filed in 1924 and issued to KITO KENZABURO disclosed a vibration isolation device using rolling bearing, in which roll balls are sandwiched between utensil type disks which are provided on opposite concave surfaces formed between the base and the bottom of the columns, so as to support the building. However, the above vibration isolation device has a low load carrying capacity, is high in cost, and thus the use range thereof is limited.
The various devices of the above vibration isolation system are all provided on the vibration isolation layer of the building, the vibration isolation layer comprises an upper layer structure, a lower layer structure and various devices of the vibration isolation system which are mounted between the upper and the lower layer structures, the upper layer structure is consisted of upper beams and/or slabs and movable bases, and the lower layer structure is consisted of lower beams and/or slabs and fixed bases. More specifically, the rolling bearing vibration isolation devices, the rubber block horizon-resetting devices and the like are all arranged between the moveable bases and the fixed bases. The above various devices carry out their functions respectively and separately. Since the spaces under the bottom of the columns of the building are limited, the values of the function parameters of the various devices to be selected are interfered with one another and difficult to set reasonably. In addition, the various devices are difficult to maintain. These are the main reasons why the above vibration isolation technique is not put into use practically until now.